Positron Emission Tomography has proved to be useful in the study of psychiatric disease such as epilepsy, neurologic disorders, brain function, cardiac metabolism, tumor detection, staging and prognosis. The PENN-PET scanner currently produced by UGM Medical Systems is designed specifically to serve the clinical needs and features a large axial field-of-view, equal resolution in all directions and a fully 3-D reconstruction method. The proposed research will lead to improved spatial resolution, improved count rate capability and more flexibility in geometry than is currently possible. The techniques to achieve this are equally applicable to single photon Anger cameras as currently used in Nuclear Medicine and these applications will also be investigated as part of the phase II work. Furthermore a new scintillator, YA1O(3)(Ce), will be investigated as an alternative to NaI(Tl).